Members of the Joinville Gladiators watch the action in a game against Porto Alegre-based Bulls FA. (Andrew Jenner/For The Washington Post)

A few years ago, late at night, bored, Felipe Rezes was flipping through channels when he stumbled across something novel: guys in helmets knocking each other down and chasing an oddly shaped ball. Now 14, Rezes has since become a Dallas Cowboys nut and an enthusiastic convert to the small but fast-growing crew of Brazilians mad for the American kind of futebol.

On this Saturday night, Rezes is wearing a grin and brandishing a camera on the sideline of a game between the Bulls FA, based in Porto Alegre — the southernmost capital city of a Brazilian state — and the Joinville Gladiators, from the neighboring state to the north. The two play in the southern conference of the Liga Nacional de Futebol Americano, a second-tier league with 14 teams this season.

If you think soccer when you think Brazil, you’re thinking right. Soccer rules, no question — though, in the meantime, American football is blowing up.

“It’s the fastest-growing sport in Brazil,” says Lucas Biazus, a Bulls linebacker sitting out the game with an injury.

The first team to play full-pad tackle football in Brazil wasn’t officially organized until the early 2000s. Today, there are more than 120 teams playing all over the country in a variety of evolving and sometimes-competing leagues.

The Bulls, getting ready to take the field vs. the Gladiators, are one of 14 teams in the Liga Nacional de Futebol Americano. (Andrew Jenner/For The Washington Post)

Tonight’s game kicks off before a few hundred fans. Some years back, the players say, they’d have been lucky to kick off in front of anyone. Now, championship games can draw thousands. There is momentum — and a steep learning curve for newbies.

“It’s really complex,” says Luana André, a 24-year-old university student up in the stands. “There are a lot of rules, so it’s really hard for someone new to understand.”

Between plays and after penalties, she turns to her boyfriend, Pedro Lunardi, for explanation. Lunardi, also a student, has loved football for a decade. Like practically every other fan here, TV was his gateway drug to the sport.

In the ’90s, ESPN began broadcasting a handful of NFL games in Brazil. That’s since grown to live broadcasts of the league’s Thursday, Sunday and Monday games and helped nurture a Brazilian fan base large enough to attract attention from league executives.

“We’ve been incredibly encouraged in the last few years . . . in the growth in popularity that the NFL seems to be enjoying” in Brazil, Mark Waller, the executive vice president of the NFL’s international division, said in a phone interview from New York. “It feels like the timing is right for us to explore what might be possible in that market.”

Ideas the NFL is now considering, Waller said, range from organizing fan viewing parties all the way up to something “much more bold”; rumors of a Rio 2017 Pro Bowl, for instance, have been making the rounds since earlier this year.

With a well-established viewership in place, football’s newest frontier in Brazil is participatory. Eager to give it a try, fans are becoming players — and discovering a new sort of football learning curve.

Lucas Bair, center, is an 40-year-old American who hadn’t played football since high school, but joined the Bulls several months ago and now plays and coaches the offensive line. (rks/Andrew Jenner/For The Washington Post)

Hardly anyone on teams like the Bulls began playing American football before their 20s, and it shows. The game is heavy on miscues and busted plays. A decent American high school team would win here. You have to cut them a break, though; These teams are made entirely from scratch. This first wave of Brazilian football players didn’t grow up tossing footballs in their back yards, and their coaches have no indigenous tradition of football wisdom and philosophy to draw from.

Instead, according to Henrique Riffel, a journalist who runs a Web site about football in Brazil, teams often consult YouTube, imitating drills they pull up online. They’re also eager to welcome anyone with any prior playing experience — especially Americans.

“If you walk onto one of these teams and you’re American, you’re immediately assumed to be the team’s savior,” says Lucas Bair, an American who did just that for the Bulls several months ago.

Bair, 40, hadn’t played football since his days as a lineman at Ankeny High School in Iowa. He thought he’d be lucky to even be allowed on the team: “Unfortunately, they got an American who’s not very good,” he said. Shortly thereafter, he found himself playing and coaching the offensive line. The biggest challenge he has faced, he says, is convincing his line that football is a fundamentally violent game.

“There’s not a lot of hard hitting. When the ball hikes, you don’t hear the popping noise of the pads,” says Bair, who works as a missionary. “That’s really hard to teach these guys. I keep telling ’em, ‘You gotta hit somebody!’ ”

By the second half, the Gladiators have built a several-possession lead, and the Bulls have managed just six points. Play turns sloppy, and flags fly. The referee announces penalties in a sort of smashmouth Creole, Portuguese peppered with un-translated jargon like “holding” and “delay of game.”

During one particularly messy stretch, consecutive penalties result in a difficult sequence of attempted and re-attempted PATs by the Gladiators. It only ends when the fourth try sails wide left, and the flag on the play — yes, there is another — is against the kicking team. Penalty declined, moving on.

The ensuing kickoff, pushed back because of unsportsmanlike conduct on the touchdown prior to the PAT debacle, sails out of bounds. This results in another flag, more “Portuguish” from the referee and yet another rulebook infraction to further confound matters for fans-in-training like Luana André.

Thousands of miles away, there is in fact one Brazilian in the NFL: Cairo Santos, a second-year player on the Kansas City Chiefs. Yes, he’s a place kicker (11 for 15 on field goal attempts this season, including a team-record 7 for 7 in a game against the Cincinnati Bengals earlier this month). The fans here are proud enough of him, but a kicker is a kicker. It may be a while before a Brazilian breaks through other than on special teams. The college pipeline isn’t deep with Brazilian talent at the moment — the NCAA is aware of just one Brazilian playing in the top-level Football Bowl Subdivision (Rafael Gaglianone of Wisconsin) and one in the second-tier Football Championship Subdivision (Henrique Ribeiro of Chattanooga). Both are kickers.

Riffel, 28, played four seasons as a cornerback for the Porto Alegre Pumpkins, the Bulls’ crosstown rivals. He figures his generation came to football too late to really master the game. The fact that his generation is playing at all, though, is definite progress for a sport that, not that long ago, was nothing more than a vague notion in the Brazilian consciousness.

Final score on this chilly, rainy night: Gladiators 26, Bulls 6. As the Bulls make their dispirited way off the field, a child runs out from the stands to meet a slump-shouldered player. In the grand scheme of Brazilian football, this is tonight’s truly significant aspect: that there are now Brazilian kids growing up around football, that they’re becoming familiar with it from the time of earliest memory as a painful, thrilling sport played by people they look up to, and that they themselves may soon pick it up.

“They’ll play better than us,” says Riffel.